Charged-particle-beam exposure apparatus and methods with substrate-temperature control

Abstract

Apparatus and methods are disclosed for increasing the throughput of a charged-particle-beam exposure apparatus. The apparatus comprises an exposure-processing chamber in which exposure of individual sensitive substrates is performed using a charged-particle beam under preset vacuum and temperature conditions. A load-lock chamber, connected to the exposure-processing chamber by a gate valve, is used to bring the sensitive substrate from atmospheric conditions to a vacuum condition in preparation for transport into the exposure-processing chamber. Means are provided for adjusting the temperature of the sensitive substrates so that, upon entry of the sensitive substrate into the exposure-processing chamber, the temperature of the sensitive substrate matches an interior temperature of the exposure-processing chamber.

What is claimed is: 
     
       1. A charged-particle-beam exposure apparatus, comprising: (a) an exposure-processing chamber in which exposure of a sensitive substrate is performed using a charged-particle beam under preset vacuum and exposure-temperature conditions;   (b) a load-lock chamber having an interior pressure that is variable between an atmospheric pressure and a subatmospheric pressure;   (c) a gate valve connecting the load-lock chamber to the exposure-processing chamber;   (d) transport means for transporting the sensitive substrate from an external environment into the load-lock chamber, and for transporting the sensitive substrate between the load-lock chamber and the exposure-processing chamber; and   (e) temperature-adjusting means for adjusting the temperature of the sensitive substrate prior to exposure-processing of the sensitive substrate in the exposure-processing chamber, the sensitive substrate being transported into the load-lock chamber under atmospheric conditions, after which the load-lock chamber is evacuated to a vacuum condition to allow the sensitive substrate to be transported from the evacuated load-lock chamber through the gate valve into the exposure-processing chamber, said temperature-adjusting means adjusting the temperature of the sensitive substrate such that, when the sensitive substrate is transported into the exposure-processing chamber, the sensitive substrate is at the exposure temperature.   
     
     
       2. The charged-particle-beam exposure apparatus of claim 1, wherein said temperature-adjusting means maintains the sensitive substrate at a temperature that compensates for heat loss to the sensitive substrate due to adiabatic expansion and other heat losses occurring as the sensitive substrate is transported from the exterior environment to inside the exposure-processing chamber. 
     
     
       3. The charged-particle-beam exposure apparatus of claim 1, wherein said temperature-adjusting means is situated inside the load-lock chamber. 
     
     
       4. The charged-particle-beam exposure apparatus of claim 3, wherein said temperature-adjusting means comprises a sensitive-substrate holder comprising a conduit through which a temperature-controlled liquid or gas is circulated. 
     
     
       5. The charged-particle-beam exposure apparatus of claim 4, wherein the sensitive-substrate holder comprises a ceramic material having a planar top surface, the top surface comprising a thin metal film layer with a thin insulator layer thereon, a dc voltage being applied to the thin metal film layer to electrostatically secure the sensitive substrate to the top surface. 
     
     
       6. The charged-particle-beam exposure apparatus of claim 3, wherein said temperature-adjusting means comprises a thermally conductive sensitive-substrate holder and a heater for heating the sensitive-substrate holder. 
     
     
       7. The charged-particle-beam exposure apparatus of claim 6, wherein the heater is a heating lamp or nichrome heater. 
     
     
       8. The charged-particle-beam exposure apparatus of claim 3, wherein said temperature-adjusting means comprises a thermally conductive sensitive-substrate holder, a conduit through which a temperature-controlled liquid or gas is circulated, and a heater for heating the sensitive-substrate holder. 
     
     
       9. The charged-particle-beam exposure apparatus of claim 1, further comprising a coater for applying a resist to the sensitive substrate, a baking chamber in which the sensitive substrate is baked at a baking temperature after the resist is applied, a cooling chamber in which the sensitive substrate is cooled after baking, and transport means for transporting the sensitive substrate from the coater to the baking chamber, from the baking chamber to the cooling chamber, and from the cooling chamber to the load-lock chamber, and wherein said temperature-adjusting means is situated in the cooling chamber. 
     
     
       10. The charged-particle-beam exposure apparatus of claim 9, wherein said temperature-adjusting cooling means comprises a temperature-controlled metal plate on which the sensitive substrate is placed to adjust the temperature of the sensitive substrate. 
     
     
       11. The charged-particle-beam exposure apparatus of claim 1, wherein said temperature-adjusting means comprises an isothermal tank containing a gas controlled to a preset temperature, wherein said transport means transports the sensitive substrate stored in the isothermal tank into the load-lock chamber. 
     
     
       12. The charged-particle-beam exposure apparatus of claim 1, wherein said temperature-adjusting means comprises an isothermal plate, wherein said transport means transports the sensitive substrates from the isothermal plate into the load-lock chamber. 
     
     
       13. A charged-particle-beam exposure apparatus, comprising: (a) an exposure-processing chamber in which exposure of a sensitive substrates is performed using a charged-particle beam under preset vacuum and exposure-temperature conditions;   (b) a load-lock chamber in which pressure is variable between atmospheric and subatmospheric;   (c) a loader chamber in which temperature is controlled;   (d) a first gate valve connecting the load-lock chamber to the loader chamber;   (e) a second gate valve connecting the loader chamber to the exposure-processing chamber;   (f) transport means for transporting the sensitive substrate between an external environment and the load-lock chamber, for transporting the sensitive substrate from the load-lock chamber and the loader chamber, and for transporting the sensitive substrates from the loader chamber to the exposure-processing chamber; and   (g) temperature-adjusting means for controllably adjusting the temperature of the sensitive substrate prior to exposure processing of the sensitive substrate in the exposure-processing chamber, wherein the sensitive substrate is transported from the external environment to the exposure-processing chamber by a sequence comprising transport of the sensitive substrate into the load-lock chamber under atmospheric conditions, evacuation of the load-lock chamber to a vacuum condition, transport of the sensitive substrate from the load-lock chamber through the first gate valve into the loader chamber, and transport of the sensitive substrate from the loader chamber through the second gate valve into the exposure-processing chamber, said temperature-adjusting means adjusting the temperature of the sensitive substrate such that, when the sensitive substrate is transported into the exposure-processing chamber, the sensitive substrate is at the exposure temperature.   
     
     
       14. A method for increasing the throughput of a charged-particle-beam exposure apparatus, wherein exposure of a sensitive substrate by a charged-particle beam occurs in an exposure-processing chamber under preset vacuum and temperature conditions, the method comprising the steps: (a) transporting a sensitive substrate into a load-lock chamber under atmospheric conditions;   (b) evacuating the load-lock chamber to a preset vacuum level to match a vacuum level in the exposure-processing chamber;   (c) transporting the sensitive substrate from the evacuated load-lock chamber into the exposure-processing chamber; and   (d) adjusting the temperature of the sensitive substrate so as to compensate for any temperature loss to the sensitive substrate during steps (a)-(c) so that the temperature of the sensitive substrate upon entering the exposure-processing chamber matches an interior temperature of the exposure-processing chamber.   
     
     
       15. A method for increasing the throughput of a charged-particle-beam exposure apparatus, wherein exposure of a sensitive substrate by a charged-particle beam occurs in an exposure-processing chamber under preset vacuum and temperature conditions, the method comprising the steps: (a) transporting a sensitive substrate into a load-lock chamber under atmospheric conditions;   (b) evacuating the load-lock chamber to a preset vacuum level to match a vacuum level in the exposure-processing chamber;   (c) transporting the sensitive substrate from the load-lock chamber into a loader chamber;   (d) transporting the sensitive substrate from the loader chamber into the exposure-processing chamber; and   (e) adjusting the temperature of the sensitive substrate so as to compensate for any temperature loss to the sensitive substrate during steps (a)-(d) so that the temperature of the sensitive substrate upon entering the exposure-processing chamber matches an interior temperature of the exposure-processing chamber.